There is known a chainless displacement system for a mining machine (see, for example, UK Pat. No. 1,529,516; Cl. E1F 17; Int.Cl..sup.2 E21C 29/02), comprising a guiding rack mounted on the working-face conveyer.
The guiding rack permanently meshes with a pair of gears rotatably mounted on the mining machine, the gears being mounted on the mining machine in pairs, secured on shafts rotatable therewith relative to the mining machine. The gears are operatively connected through the rotating mechanism with hydraulic cylinders adapted to actuate the gears for rolling along the rack.
The rotating mechanism of each gear includes toothed racks secured on the ends of the piston rods of the hydraulic cylinders and extending axially of the cylinders.
The rotating mechanism further includes pinions which are mounted on the shafts of the gears and are operatively connected therewith through clutches, these pinions meshing with the toothed racks of the hydraulic cylinders. With the hydraulic cylinder performing its working stroke, the toothed racks rotate the pinions which drive the gears through the intermittently engageable clutches. The gears, the intermittently engageable clutches and the pinions are mounted successively along the axes of the respective shafts.
The displacement of the mining machine, e.g. a mining cutter-loader along the working-face is effected by making one pair of the gears roll along the guiding rack, while the other pair of the gears stays in a preparatory cycle during which the hydraulic cylinders associated therewith are actuated through the return stroke.
With this design of the rotating mechanism incorporating the abovementioned intermittently engageable clutch, the entire chainless displacement system is bound to have relatively large dimensions, particularly, if it is intended to transmit efforts in the 20-30 ton range.
Furthermore, with the successive arrangement of the gears, intermittently engageable clutches and pinions, the dimensions of this chainless displacement system of the prior art in the direction of their arrangement are likewise relatively great. This fact virtually precludes the incorporation of this chainless displacement system of the prior art in a mining cutter-loader intended for operation in thin seams.